Transmitting handwriting and pictures



Patented Sept. 29, 1925.

VUruTiezn STATES PATENT oFrlcr-J.

GILBERT VERNAM, OF BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND' TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TRANSMITTINQ 'HANDWRITING AND PICTURES.

Application filed July 12, 1923. Serial No. 651,111.

T 0 all 107mm t may concern:

Be it known that I, GILnr-:n'r' S. VnnNAM, residing at Brooklyn, in the county of Kings and State of New York, have inventedv certain Improvements in Transmitting Handwriting and Pictures, of which thefollowing is'a specification.

This invention relates to the secret transmission of intelligence by electric currents -or otherwise, particularly'the transmission of graphic records consisting of handwriting, diagrams, pictures and the like. The object of the invention is to provide .a syrtem for enciphering and deciphcring such records, when. transmission is to be by electric currents the result is, in general effected by altering the transmitting currents according to some rule or code, so that it' the transmission line is tapped the impulses taken oit will produce an unintelligible record. At 'the receiving end, the signalv impulses maybe restored to theirl original form'before acting upon the receiving device so as to reproduce the original writing or picture at the receiving station, orA

the enciphered signal impulses may beused to produce 4the writing or dlagram inciphered form, and this may be deciphered at any desired-time or placeby the .use of suitable apparatus operating according` to the same rule or code. The invention may also be used to mechanically encipher handwriting or the like so as to produce a. written record in unintelligibleA form which may then be transmitted electrically or in any otherdesired manner and deciphered mechanically at the receiving end. The invention will be described more in detail in connection with the accompanying drawings in which Figure 1 represents one form of the invention. Fig. 2 represents a modification in which Vthe enciphering is accomlished mechanically; and Fig. 3 represents a detail of theapparatus shown in Fig.

Referring to Fig. 1, 10 and 11 represent respectively the sending and receiving apparatus of the ordinary telautograph. The sending station. 10 comprises two resistance elements 13. and 14 over which-travel the rheostat arms 15 and 1G which are ,con-

itrolled by link motions from the point 18 at which may be locateda tracing instrument or pencil. Each of the resistances constitutes a potentiometer connected across the battery 20, and the arms 15 and 16 are connected respectively to transmission lines 21 and 22. As is well known, this apparatus serves to transmit over. the lines 21 andA 22 varying currents representing respectively components of the movement of In. accordance with the present invention the currents transmitted by such an apparatus are Avaried between the transmitting and receiving stations, so that the currents on .the line do not represent components of the movement of the. point 18 of the trans-- lnitting apparatus. In Fig. 1 this is accomplished by imposing upon the lines additional electromotive forces which are varied in a prearranged manner. For this purpose, resistances 34, 35, in the form of closed loops with. circularly arranged contact points, may be used, as indicated, with diametrically opposite points on each resistance bridged by a circuit including a ba*- .tery or other source of potential 36, 37.

The lline wires 21, 22Aare connected to the bridges containing these sources, and the outgoing lines. 38, 39 are connected respectively to the arms 40 and 41 which rota-te over the contacts of resistances 34, 35, respectively. It may be found desirable to make one orv both of the circularly arranged resistance elements vary in amount for given angular distances asv is indicated `by the variation inthe resistance element 35. The arms 40 and 41 may bedriven in any predetermined manner and by any convenient means.

At the receiving end are two resistance elements 42 and 43 corresponding exactlyto the elements 34 and 35, respectively.

Sources of current 44, 45, corresponding to tions produced in the signaling impulses by' the rotating arms 40 and 41, and these iin-,

tional potentials imposed upon the line con' currently with the lsignal impulses are continually varied vby the rotating arms 40, 41 with the result that the currents found in the transmitting lines 38, 39, should these be tapped by anlunauthorized individual,.

would not 'produce an intelligible record when applied to the ordinary telautograph apparatus or any other receiving apparatus` unless 'it were provided with the precise 4deciphering mechanism herein described." At' the receiving station, as described, current impulses-are produced by the rotating'arms 47 and 48` passing over the potentiometers 42 and 43 which are identical with thevariapulses being applied to the coils 50 and 451 in the proper phase relation will exactly counteract in the receiving magnets 24 and 25 the variations produced by the enciphering mechanism, sothat the recording pencil 29 will produce the handwriting, diagram' or other graphic record as it is traced 'at the point 18.

In Fig. 2 I have 'shown an arrangement for enciphering mechanically. In. this figure, and 6l -represent respectively the trans# mitting and receiving mechanism of the or-.

dinary telautograph. At the transmitting end only the resistances 62-and the link motion 63 for varying'thel resistancesv are shown' in detail; and at the receiving end'only' the? controlling magnets 64' and theA recordinglink motion 65 are shown in detail. Insteadv vof forming letters ordiagrams to be transmitted by tracing them. at the point 66, as in the ordinary telautograph, this point of the link motion is connecte suitable mechanical movement; and the fig ure to be transmitted is traced lby another point of the pantograph, as at 70. 'Means are then provided for causing a given movement of the point to be reproduced in the link motion of .the telautograph in a variedA or changed form.4 In the apparatus here shown by way of illustration, this is accomplished by connecting the point 68 of the pantograph to the point 66 of the telautograph through an arm 72 which is' arranged to be rotated by a gear 734 driven by a rack 74 which has one end fixed to the fixed oint 76 of the telautograph. A spring 7 or other convenient means, is arranged to maintain the gear and rack in an engagement.

At the receiving end an exactlycorrespondto one point. 68 v03E a pantograph 69, or some other similar or ing pantograph' 0r mechanical movement 8O 1s arranged tofconnec't the usual recording point 81 of the telautographto the record ing point 82 of the deciphering apparatus.

NVth the apparatus thusarranged, it will ybe seen that a given movement of the point 70 at the transmitting end will cause not only a corresponding movementof the point-68v of the telautograph, but w'illcaus'e al rotation of the gear'73 on thev axis 68 vdue to its engagementfwith the rack' 74. This rotation will, of course, cause the point 66 to produce amovement additional to that represented by the movement of the-point 70, this-movementbeingin accordance with the ixed rule represented by the designand arrangement of the gearing here shown. The altered movement of the point 66 will be reproduced :by telautograph apparatus at the -point 81,

so that if the writing or drawing beftraced by a record-ing instrument at-eit'h-er. the point 66 or the pointz81, it will bein an unintelligibleform.; The movement of-.the point'8l, in accordance with theV movement of the "point 66,4 will, however, cause'a movement'.

of the pantograph 80 and the gearing 823-84 connected thereto', which' willexactly counteract the enciphering effect of the gearing 73-7 4 at the transmitting end, with the' result that'the point 82 will record correctlyA the ligure traced atv the point 70.

As heretofore pointed out,y the Vfigure may be recorded at the transmitting station in the enciphered form and transmitted in anydesired way and deciphered whereve-rdesired 'byemploying'anapparatus similar to that used in enciphering. Thus the apparatus .shown in Fig. 2 may be used for recording the mechanically enciphered figure at the point 66 or for deciphering messages which have elsewhere been enciphered by-asimilar apparatus :and transmitted to that point by --mail or otherwise. And'if a'message be enciphered mechanically at the point 66, it

may be transmitted to the receiving station of Fig. 2 andthere deciphered on the appar'atus 80. It has been found that when an enciphered figure is to be deciphered by mechanically tracing it in the manner just suggested, theremay b e points at which the lproperdirection of movement of the tracing pencil on"the enciphered igure is doubtful due to the presence of'small loops or crossi'ng lines, or the like. The tracing in such ,cases is; much facilitated if two 'tracing points are used on both the enciphering and deciphering apparatus. have shown a second tracing point 85 at the lefthand station and a second tracing'point 86 at the right-hand station. Each point lThus in Fig. 2 I

will produce an.,enciphered form of the ig- 'suitable for varying the current in the line according to any predetermined rule or code may be substituted for the mechanism 34- 41 shown in Fig. l and for the corresponding deciphering mechanism at-the receiving end; and any Ameans -for ,varying the ratio of movement of the arms of the pantograph may be substituted for the gearing illus'- trated in Figs. 2 and 3.

What I claim is: 4 1. In an apparatus for enciphering graphic figures the combination of an instrument for tracing the gure to be enciphered, mechanismv associated with ysaid instrument for :resolving movement of a given point in'said mechanism into 'a pluralit of components, a plurality of trans- ,f mittmg circuits, means .for supplying `said circuits with current, means for causing' a variation of the current in the several cir-- cuits in response to variations in said components respectively,"and means for concurrently causing other variations in said currents which'are independent of the movee ment of said given point in accordance with the figure to be enciphere'v v 2. In an apparatus for enciphering the combination of an instrumechanism associated with said instrument for resolving movement of a given point in said mechanism into a plurality of components, a plurality of transmitting circuits,

means for supplying said circuits with currents, means for causing avariation ofthe current in the several clrcuits 1n response to variations insaid components respectively,` and means for eiiecting concurrently `name to this specification other variations in the currents of one or more of said circuits which are independent of the c omponents of movement of said tracingv instrument, and which follow some vpredetermined rule. f

3. In a system for enciphering telautographic transmission of graphic iigures the combination of aninstrument for tracing the 'figure to be transmitted, va telautograph said arms in accordance with the figure to be transmitted.

4. A secretl transmission system for graphic figures comprising an instrument for tracing the figure to be transmitted, a telautograph transmitter, including arms associated with said Iinstrument for causing a plurality of varying electric currents representing in value,respectively, the degree of movement of said` arms, means forvcausing variations in said currents which -do not correspond to components of the movement of said tracing instrument, anda te1auto. graph receiving apparatus, including means for counteracting the effect of said last named, variations of said electric currents whereby the recording pencil of )said receiving apparatus. reproduces correctly the tigure traced by said instrument.

5. The method of enciphering graphic figures which consists in tracing the figure,

representing thetraci movement by a plu-l rality of changinggva ues instantaneously corresponding to cofmponents of said movements, and varying one or more'of said changing values during the tracing, in accordance With some predetermined rule.

In testimony whereof, I have signed my this 10th dayv of July 1923.

GILBERTY s. VERNAM. 

